The invention relates to a quartz oscillator comprising two transistors whose collectors are connected each one via a collector impedance to a pole of a direct voltage source and each one via at least one semiconductor junction to the base of the other transistor, a two-terminal network comprising a quartz resonator being connected to the emitter of one transistor.
Such a quartz oscillator is disclosed in U.S. Pat. No. 3,824,491, in which the emitters of the two transistors are connected each one via a direct current source to ground and interconnected via the two-terminal network incorporating the quartz oscillator. All the transistors are of the same conductivity type, so that basically the circuit can be manufactured in integrated circuit form. However, two terminals are required to connect the two-terminal network to the quartz.
In addition, the periodical "Funkschau" 1980, volume 20 discloses a quartz oscillator comprising two transistors of the opposite conductivity type which each have a collector and an emitter impedance and whose base terminals are directly connected to the collector branch of the other transistor, the two-terminal network incorporating the resonator being arranged in parallel with an emitter resistor. However, as the transistors are of the opposite conductivity type, this circuit can hardly be manufactured in integrated circuit form. Furthermore there is the risk that the collector-base diode of at least one of the transistors becomes conductive and that this transistor becomes saturated. The reduction of the charge carrier connected thereto in the transistor results however in delays which cause that, at least at frequencies of 5 MHz and higher, the oscillator frequency is no longer determined by the quartz crystal alone.